Plating method

ABSTRACT

A cathode potential is applied to a conductive layer formed on a substrate having a depression pattern. A plating solution in electrical contact with an anode is supplied to the conductive layer to form a plating film on the conductive layer. At this time, the plating solution is supplied by causing an impregnated member containing the plating solution to face the conductive layer. Since the plating solution stays in the depression, a larger amount of plating solution is supplied than on the upper surface of the substrate, and the plating rate of the plating film in the depression increases. Consequently, the plating film can be preferentially formed in the depression such as a groove or hole.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 11-033234, filed Feb. 10,1999, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an electroplating technique and, moreparticularly, to a plating method and plating apparatus for asemiconductor device.

In recent years, copper has received a great deal of attention as aninterconnection material in order to reduce the interconnectionresistance of an LSI and improve its reliability. The copperinterconnection forming methods include CVD, sputter reflow, andplating. Of these methods, plating is simple in process and low in cost,exhibits high filling performance, and can form a high-performanceinterconnection.

However, currently available plating apparatuses do not satisfactorilyconsider a semiconductor device manufacturing process. The conventionalapparatus basically adopts a “plating bath” method following the platingindustry. According to this method, a semiconductor substrate is platedby dipping it in a plating bath or cup filled with a plating solution.

This classical plating method has not achieved progression particularlyconsidering the semiconductor device manufacturing process. Thus, whenthe method is applied to the semiconductor device manufacturing process,the following serious problems arise.

(1) It is difficult to perform precise control of an absolute filmthickness in nanometers that is much smaller than the film thickness ina general plating industry, and to ensure high uniformity on thesubstrate surface.

(2) Bubbles and dust greatly influence the semiconductor process towhich a very low defect density on a fine pattern is demanded.

(3) A voltage/current from a cathode can only be applied from theperiphery of a substrate outside a region where a pattern is formed. Ifthe electrode is brought into contact with the inside of the substratewhere the pattern is formed, scratches or dust is generated to decreasethe product yield. This is disadvantageous in a situation in which thewafer size in the semiconductor process is increasing year by year. Thatis, the conductive layer of an electroplating solution must be madethick on the wafer surface. Otherwise, the resistance from the cathodepotential supply portion at the periphery of the substrate to the centerof the substrate increases, failing to ensure the plating current at thecenter. However, the thickness of the conductive layer is limited byprocess constraints.

(4) It is difficult to perform locally plating in accordance with aregular pattern formed on a semiconductor substrate. It is alsodifficult to perform positive control of the film thickness on thesurface of a semiconductor substrate (wafer), for example, to make theperiphery thick in accordance with requirements in a post-plating step(e.g., CMP). If the plating solution is not wanted to attach to thelower surface of the substrate in order to prevent contamination of thesubstrate or the like, a special seal must be used to protect the lowersurface.

(5) In forming a film into a three-dimensional pattern, film formationon projections cannot be suppressed. An example of the most typicalapplications of a plating metal film among semiconductor processes isformation of a metal film for forming a damascene interconnection. Inthe damascene process, a plating metal is buried in an interconnectiongroove or hole, and a metal film formed outside the groove or hole isremoved by CMP or the like. Considering load reduction in a subsequentCMP step or the like, formation of the plating film on a portion exceptfor the groove or hole must be prevented as much as possible. Theabove-described requirements and problems unique to the semiconductorprocess obstruct the use of plating.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a plating method andplating apparatus which can easily perform precise control of theplating film thickness and are hardly influenced by bubbles and dust.

It is another object of the present invention to provide a platingmethod which realizes preferential formation of a plating film to agroove or hole suitable for the damascene process.

It is still another object of the present invention to provide a platingmethod and plating apparatus capable of performing local plating.

To achieve the above objects, according to the first aspect of thepresent invention, there is provided a plating method comprising thesteps of

-   -   preparing a substrate to be processed which has a base plate and        a conductive layer formed on at least part of the base plate,    -   applying a potential of a cathode to the conductive layer,    -   causing a first impregnated member containing a plating solution        in electrical contact with an anode to face the conductive        layer, and    -   relatively moving at least part of the first impregnated member        with respect to the conductive layer in order to form a plating        film on at least part of the conductive layer.

The step of relatively moving at least part of the first impregnatedmember with respect to the conductive layer desirably includes the stepof vertically moving the at least part of the first impregnated memberwith respect to the conductive layer.

The step of vertically moving at least part of the first impregnatedmember with respect to the conductive layer desirably includes the stepof moving the anode in contact with the first impregnated member apartfrom the conductive layer in accordance with plating of the platingfilm.

The step of vertically moving at least part of the first impregnatedmember with respect to the conductive layer may include the step ofcontrolling at least one of a moving speed of relative movement in avertical direction and an application current in accordance with platingof the plating film.

The step of vertically moving at least part of the first impregnatedmember with respect to the conductive layer desirably includes the stepof forming a plating film while alternately repeating an operation ofcausing the conductive layer and the first impregnated member to faceeach other and an operation of dipping the first impregnated member intoa plating bath containing the plating solution.

The step of connecting the cathode to the conductive layer desirablyincludes the step of connecting the cathode to the conductive layer bybringing a second impregnated member which contains an electrolyticsolution and is connected to the cathode into facing the conductivelayer in a different region from a region where the first impregnatedmember comes into facing the conductive layer.

The second impregnated member can perform the same relative movement asthe first impregnated member.

The plating method desirably further includes the step of measuring afilm thickness of the plating film by a film thickness measuringmechanism arranged on the conductive layer in a different region from aregion where the first impregnated member comes into facing theconductive layer.

The plating method desirably further includes the step of additionallyforming the plating film by bringing the impregnated member into facingthe conductive layer in accordance with a measurement result of the filmthickness measuring mechanism.

The film thickness measuring mechanism desirably performs the samevertical movement as the first impregnated member.

The step of vertically moving at least part of the first impregnatedmember with respect to the conductive layer can include the step ofbringing at least part of the first impregnated member into contact withthe conductive layer.

The step of relatively moving at least part of the first impregnatedmember with respect to the conductive layer can include the step ofhorizontally moving at least part of the first impregnated member withrespect to the conductive layer.

The step of horizontally moving at least part of the first impregnatedmember with respect to the conductive layer desirably includes the stepof bringing at least part of the first impregnated member into contactwith the conductive member, and moving the plating solution on an uppersurface of the base plate into the depression pattern formed in advancein the upper surface of the base plate by sliding movement.

According to the second aspect of the present invention, there isprovided a plating method comprising the steps of

-   -   preparing a substrate to be processed which has a base plate and        a conductive layer formed on at least part of the base plate,    -   applying a potential of a cathode to the conductive layer,    -   causing a first impregnated member containing a plating solution        in electrical contact with an anode to face the conductive        layer, and    -   forming a plating film on at least part of the conductive layer        while controlling a film thickness profile.

The step of forming a plating film on at least part of the conductivelayer while controlling a film thickness profile desirably includes thefollowing steps:

-   -   1) the step of making a film thickness on a depression pattern        of the base plate larger than a film thickness on an upper        surface of the base plate, the base plate having the depression        pattern on a surface thereof;    -   2) the step of controlling at least one of a stay time of the        impregnated member on the conductive layer and an application        current value supplied between the anode and the cathode;    -   3) the step of setting the anode having a desired pattern on the        impregnated member;    -   4) the step of controlling a flat distribution of a current        flowing through the conductive layer by either one of an        electrode and an insulator with a desired pattern formed inside        the impregnated member;    -   5) the step of using the impregnated member having a desired two        dimensional distribution of a supply amount of plating solution        to the conductive layer.    -   6) the step of relatively moving the impregnated member and an        upper surface of the base plate in a facing plane direction,        thereby decreasing the plating solution on the upper surface of        the base plate, the base plate having a depression pattern on        the surface; and    -   7) the step of bringing part of the impregnated member into        contact with the conductive layer and controlling a film        thickness in accordance with whether the impregnated member is        in contact with the conductive layer.

According to the third aspect of the present invention, there isprovided a plating method comprising the steps of

-   -   preparing a substrate to be processed which has a base plate and        a conductive layer formed on at least part of the base plate,    -   applying a potential of a cathode to the conductive layer, and    -   forming a plating film on at least part of a region by causing        an impregnated member containing a plating solution in        electrical contact with an anode to face the conductive layer,    -   wherein the step of forming a plate film includes the step of        forming a plating film while alternately repeating an operation        of causing the conductive layer and the impregnated member to        face each other and an operation of moving the impregnated        member to a remote location where a plating current is        interrupted between the anode and the cathode.

The operation of moving the impregnated member to a remote locationdesirably includes an operation of dipping the impregnated member into aplating bath containing the plating solution.

According to the fourth aspect of the present invention, there isprovided a plating method comprising the steps of

-   -   preparing a substrate to be processed which has a base plate and        a conductive layer formed on at least part of the base plate,    -   causing an impregnated member containing a plating solution in        electrical contact with an anode to face the conductive layer in        order to form a plating film in at least part of a region, and    -   connecting a cathode to the conductive layer by causing another        impregnated member which contains an electrolytic solution and        is connected to the cathode, to face the conductive layer in a        different region from a region where the impregnated member        comes into contact with the conductive layer.

The conductive layer may be in contact with at least one of theimpregnated member and the another impregnated member.

The another impregnated member can perform the same sliding movement asthe impregnated member.

According to the fifth aspect of the present invention, there isprovided a plating method comprising the steps of

-   -   preparing a substrate to be processed which has a base plate and        a conductive layer formed on at least part of the base plate,    -   causing an impregnated member containing a plating solution in        electrical contact with an anode to face the conductive layer in        order to form a plating film in at least part of the conductive        layer,    -   connecting a cathode to the conductive layer by causing another        impregnated member which contains an electrolytic solution and        is connected to the cathode, to face the conductive layer in        another region than a region where the impregnated member faces        the conductive layer, and    -   measuring a film thickness of the plating film by a film        thickness measuring mechanism arranged on the conductive layer        in still another region than a region where the impregnated        member faces the conductive layer.

The plating method desirably further includes the step of additionallyforming the plating film by causing the impregnated member to face theconductive layer in accordance with a measurement result of the filmthickness measuring mechanism.

The film thickness measuring mechanism desirably performs the samehorizontal movement as the impregnated member.

According to the sixth aspect of the present invention, there isprovided a plating apparatus for forming a plating film on a conductivelayer formed on at least part of a surface of a substrate, comprising

-   -   a power supply for supplying an anode potential and a cathode        potential, the cathode potential being applied to the conductive        layer,    -   an anode for receiving the anode potential,    -   a first impregnated member which has a first and a second major        surface, is in contact with or faces at least a partial region        of the conductive layer on the first major surface, is in        contact with the anode on the second major surface, holds a        plating solution, and supplies the plating solution to the        conductive layer,    -   a plating solution supply mechanism for supplying the plating        solution to the first impregnated member, and    -   a first controller for controlling formation conditions of the        plating film.

The plating apparatus desirably further includes the followingarrangements.

1) The plating apparatus further comprises a second controller forcontrolling a gap between the substrate and the first impregnated memberfacing the substrate in accordance with plating of the plating film.

2) The plating apparatus further comprises an insulating member formedto surround a side portion of the first impregnated member and a sideportion of the anode in contact with the second major surface of thefirst impregnated member, and a second impregnated member which isadjacent to the first impregnated member through the insulating member,holds an electrolytic solution, supplies the electrolytic solution tothe conductive layer, and receives the cathode potential.

3) The plating apparatus further comprises an insulating member formedalong a side surface of an opening formed through the first impregnatedmember and the anode in contact with the second major surface of thefirst impregnated member, and a second impregnated member which isformed in the opening through the insulating member, holds anelectrolytic solution, supplies the electrolytic solution to theconductive layer, and receives the cathode potential.

4) The plating apparatus further comprises a first moving mechanism forchanging relative positions of the conductive layer and the firstimpregnated member in a contact or facing plane direction.

5) The anode has at least one through hole, and the plating solutionsupply mechanism supplies the plating solution to the first impregnatedmember through at least one through hole formed in the anode.

6) The plating solution supply mechanism comprises a plating bath filledwith the plating solution, and a second moving mechanism for moving thefirst impregnated member in contact with or facing at least the partialregion of the conductive layer, and dipping the first impregnated memberin the plating bath.

7) The plating apparatus further comprises a sensor for sensing a gapbetween the anode and the conductive layer, and a third controller foradjusting the gap between the anode and the conductive layer inaccordance with a detection result.

8) The plating apparatus further comprises a composition sensor forsensing a composition ratio of the plating solution contained in theimpregnated member, and a composition adjusting unit for adjusting acomposition of the plating solution for the impregnated member inaccordance with a sensing result of the composition sensor.

9) The plating apparatus further comprises a fourth controller forcontrolling at least one of a stay time during which the impregnatedmember stays on at least part of the conductive layer, and anapplication current value between the anode and the conductive layer.

10) The anode is formed with a desired pattern.

11) The plating apparatus further comprises either one of an electrodeand an insulator with a desired pattern formed inside the firstimpregnated member.

12) The first impregnated member has a desired distribution as a supplyamount distribution of the plating solution to the conductive layer.

13) The plating apparatus further comprises a fifth controller forslightly vibrating the first impregnated member up and down, and rightand left upon energization.

14) The plating apparatus further comprises at least one strainerarranged inside the first impregnated member, near a facing portionbetween the first impregnated member and the conductive layer, in orderto drain the plating solution.

With these arrangements, the present invention attains the followingoperation effects.

According to the plating method of the present invention, an impregnatedmember containing a plating solution is placed on a substrate to beprocessed. An anode is set on the impregnated member, whereas a cathodeis connected to the substrate. Unlike the plating bath method, theplating method of the present invention can control the plating rate ofa plating film to be formed, by controlling the stay time of theimpregnated member on a member to be plated, the application currentvalue, the pattern of the anode, the pattern of an intermediateelectrode or insulator formed in the impregnated member, or the supplydistribution of the plating solution to the impregnated member. Thisfacilitates control of the plated thickness.

A through hole is formed in the anode, and bubbles in the platingsolution held by the impregnated member can be removed to suppressdefects of the plating film caused by the bubbles. Further, theimpregnated member and substrate are relatively moved in the directionof the contact plane. This prevents bubbles or dust in the platingsolution supplied to the substrate surface from staying at one portion.Defects of the plating film are therefore suppressed.

If plating using the impregnated member is done for a conductive layerformed on a substrate surface having a depression pattern of grooves orholes, the plating solution stays in the depression, and the supplyamount of plating solution to the depression becomes larger than on theupper surface of the substrate. Hence, the plating rate of the platingfilm on the surface of the depression becomes higher than on the uppersurface of the substrate. Preferential formation of the plating film inthe groove or hole can be realized to form a plating film suitable forthe damascene process. By relatively moving the impregnated member andsubstrate in the direction of the contact plane, the surface of theplating film formed on the upper surface of the substrate ismechanically polished by the impregnated member. More preferentialformation of the plating film in the groove or hole can be achieved.

Even if the impregnated member is not in contact with the substrate tobe processed, a dynamic pressure is generated in the plating solutiondue to relative movement. A pressure difference between an inside and anoutside of the depression caused by the dynamic pressure can make theplating rate greater in a groove or a hole than that on the uppersurface of the substrate.

The depression in the surface of the plating film formed finally isshallower and smoother than the depression in the substrate, whichfacilitates a subsequent smoothening step using chemical mechanicalpolishing.

The plating solution can be selectively supplied to the substratesurface using an impregnated member smaller in size than the substrate.Consequently, a plating film can be locally formed. Since the platingfilm is formed at only a portion on the substrate where the anodeexists, the plating film can be locally formed even using an anode of adesired pattern.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe invention, and together with the general description given above andthe detailed description of the preferred embodiments given below, serveto explain the principles of the invention.

FIG. 1 is a sectional view showing a schematic structure around aplating head to explain a plating method according to the firstembodiment of the present invention;

FIG. 2 is a sectional view showing a plating film having a smoothprofile that is formed by the plating method of the present invention;

FIG. 3A is a sectional view around a plated portion showing thepositional relationship between an impregnated member and anode;

FIG. 3B is a graph showing the relationship between the film thicknessof a plating film formed by the structure of FIG. 3A and the distancefrom the edge of the anode;

FIG. 4 is a schematic view showing a conventional cup type platingapparatus;

FIGS. 5A and 5B are views showing a structure for forming acharacteristic estimation plating film by impregnation, in which FIG. 5Ais a plan view and FIG. 5B is a sectional view taken along the line5B-5B in FIG. 5A;

FIG. 6 is a graph showing the comparison between the characteristics ofplating films respectively formed by a conventional plating method (cupmethod) and the impregnation method of the present invention;

FIG. 7A is a schematic view for explaining a plating method according tothe second embodiment of the present invention;

FIG. 7B is a sectional view showing part of a section taken along theline 7B-7B in FIG. 7A;

FIG. 8 is a sectional view around a plated portion schematically showingthe contact surface between an impregnated pad and a plating film formedin the second embodiment;

FIG. 9A is a sectional view showing a plating film formed in the secondembodiment;

FIG. 9B is a sectional view showing a conventional plating film;

FIG. 10 is a graph showing the dependency of plating rate on pressuresapplied to the impregnated pad, comparing that of a plating film formedon a surface of a substrate to be processed and that of a plating filmformed in a depression of the surface;

FIGS. 11A and 11B are views showing the schematic structure of a platingapparatus according to the third embodiment of the present invention, inwhich FIG. 11A is a perspective view and FIG. 11B is an enlargedsectional view taken at the portion 11B in FIG. 11A;

FIG. 12 is a block diagram showing the schematic arrangement of theplating apparatus according to the third embodiment of the presentinvention;

FIG. 13 is a sectional view showing the connected portion between thecathode contact of the plating apparatus and a conductive layer in thethird embodiment;

FIG. 14A is a conceptual view for explaining a plating method ofscanning a substrate to be processed with an impregnated cloth;

FIG. 14B is a graph showing the positional dependency of a platingcurrent value on the substrate according to the plating method in FIG.14A;

FIGS. 15A to 15C are a view and graphs, respectively, showing thepositional dependency of a plating film formed at a constant voltage ona substrate to be processed, in which FIG. 15A is a view for definingthe direction, FIG. 15B is a graph showing positional dependency in adirection indicated by a solid line in FIG. 15A, and FIG. 15C is a graphshowing positional dependency in a direction indicated by a dotted linein FIG. 15A;

FIG. 16 is a view showing the schematic structure of a plating apparatusaccording to the fourth embodiment of the present invention;

FIG. 17 is a sectional view showing the schematic structure of the mainpart of a plating apparatus according to the fifth embodiment of thepresent invention;

FIG. 18 is a sectional view showing the schematic structure of the mainpart of a plating apparatus according to the sixth embodiment of thepresent invention;

FIGS. 19A to 19D are sectional views each showing a plating bump formedby the plating apparatus according to the sixth embodiment;

FIG. 20 is a sectional view showing the schematic structure of a platingapparatus (impregnated pad) according to the seventh embodiment of thepresent invention;

FIGS. 21A to 21D are sectional views, respectively, showing steps inmanufacturing an impregnated pad according to the seventh embodiment;

FIGS. 22A and 22B are sectional views, respectively, showing steps inmanufacturing an impregnated pad according to a modification of theseventh embodiment;

FIG. 23 is a sectional view showing the schematic structure of animpregnated pad according to another modification of the seventhembodiment;

FIG. 24 is a sectional view showing the schematic structure of animpregnated pad according to still another modification of the seventhembodiment;

FIG. 25 is a sectional view showing the schematic structure of the mainpart of a plating apparatus according to the eighth embodiment of thepresent invention; and

FIG. 26 is a schematic sectional view around a plated portion in a casewhere the impregnated pad is apart from the conductive layer in thesecond embodiment.

DETAILED DESCRIPTION OF THE INVENTION

“Impregnation” in the present invention means a state in which a platingsolution is held by an impregnated member such as a solid, mixture of asolid and liquid, or mixture prepared by mixing a gas in a mixture of asolid and liquid. The plating solution is limited to a certain degree inspatial movement, compared to the case in which the plating solution issolely contained in a vessel. The impregnated member comes into contactwith a substrate to be processed, and then the plating solution acts onthe substrate. In some cases, part of the impregnated member may notcontact the substrate. Even in this case, however, the plating solutionmay be supplied to the substrate (by, e.g., a surface tension) near thefacing portion between the impregnated member and substrate. This statemay be accepted depending on the purpose of a technique to beimplemented, or can be avoided if the state is disadvantageous for thepurpose of a technique to be implemented.

Standard conditions of copper plating used in the following embodimentsare as follows:

-   -   Temperature: 25° C.    -   Current Density: 5 mA/cm²    -   Plating Rate: up to 100 nm/min    -   Anode Material: Phosphorous Containing Copper    -   Wafer: A 30-nm thick Ta film and 100-nm thick Cu film are        sequentially sputtered on an Si substrate.        These process conditions are merely standard ones for        convenience in describing the embodiments of the present        invention. The plating metal and respective parameters can be        properly changed without departing from the spirit and scope of        the present invention.

Embodiments of the present invention will be described below withreference to the accompanying drawings.

FIRST EMBODIMENT

In the first embodiment, the principle of a plating method according tothe present invention will be explained. FIG. 1 is a sectional viewshowing the schematic structure of a plating apparatus according to thefirst embodiment of the present invention. A substrate 100 to be platedhas a base plate on which an insulating film 102 with a groove patternis formed on an Si substrate (semiconductor substrate) 101, and aconductive layer 103 formed on the surface of the insulating film 102.The conductive layer 103 is a multilayered film made of a 30-nm thickTaN film and 100-nm thick Cu film. The Si substrate 101 is an 8-inchwafer. Eight needle-like cathode contacts 120 are uniformly set at theoutermost periphery of the conductive layer 103 formed on the surface ofthe Si substrate 101.

A plating head 110 is placed on the surface of the conductive layer 103.The plating head 110 is constituted by an impregnated pad (impregnatedmember) 111 which is directly placed on the conductive layer 103 andcontains a plating solution, and an anode 112 which is made ofphosphorous containing copper, set on the impregnated pad 111, andconnected to a power supply 113. The impregnated pad 111 is formed fromPVA (Polyvinyl Alcohol). The diameter of the impregnated pad 111 may belarger or smaller than or equal to that of the substrate 100.

In addition to PVA, the impregnated pad 111 may be made of a porousceramic, indefinite material such as a silica gel or agar, or materialprepared by knitting porous Teflon, polypropylene, or the like into afiber or forming such material into a sheet. The porosity or pore sizeis not uniquely determined, and changes depending on the viscosity of aliquid, the wettability and surface tension between the impregnatedmember and liquid, and the like. The impregnated pad basically sufficesto achieve a state in which the pad can hold a liquid to limit theliquid in spatial movement (for example, most of the liquid is preventedfrom flowing out without any catch tray).

An actual plating process will be explained. The pad 111 is dipped in aplating solution at 25° C. filled in a plating bath (not shown) toimpregnate the pad 111 with the plating solution. The composition of theplating solution is copper sulfate pentahydrate (CuSO₄.5H₂O):250g/Liter, sulfuric acid (H₂SO₄):180 g/Liter, hydrochloric acid (HCl):60mg/Liter. Additives such as a polymer and complex compound are added forvarious purposes such as the pH of the plating solution, stabilizationof the plating solution, protection of the anode, surface smoothness ofa formed film, and control of the crystal grain of the formed film.

By bringing the impregnated pad 111 into tight contact with theconductive layer 103, the plating solution is supplied from theimpregnated pad 111 to the surface of the conductive layer 103. Then, acurrent having a current density of 5 mA/cm² is supplied from the powersupply 113 to the anode 112. When the current is supplied to the anode112, a copper plating thin film is formed on the surface of theconductive layer 103 electrically connected to the cathode contacts 120.Note that the average plating rate of the copper plating thin film wasabout 100 nm/min.

As shown in FIG. 1, a plating solution 114 oozing out from theimpregnated pad 111 stays in depressions 104. For this reason, theplating supply amount to the depressions 104 is larger than on an uppersurface 105 of the substrate 100. Since the supply amount of platingsolution having a degree of freedom for spatial movement is large, theplating rate of the plating film on the conductive layer 103 in eachdepression 104 is higher than on the conductive layer 103 on the uppersurface 105. Thus, as shown in FIG. 2, a plating film 106 to be finallyformed has smoother steps than the stepped pattern of an insulatingfilm. Generation of dishing can therefore be suppressed to facilitatesmoothening in a subsequent planarization step using CMP (ChemicalMechanical Polishing) or the like.

A sample like the one shown in FIG. 3A was fabricated and plated withcopper. The sample had the following structure. An impregnated pad 111containing a plating solution was placed on a Cu film 107 on an Sisubstrate 101, and an anode 112 having an edge at a position apart fromthe edge of the Si substrate 101 was set on the impregnated pad 111.

As shown in FIG. 3B, the film thickness distribution of the formedcopper plating film reveals that the film thickness decreases at aposition farther away from the edge of the anode 112. By forming theanode into a desired pattern, the plating film can be selectively formedin accordance with the anode pattern.

In comparison, a copper plating thin film was formed by a platingapparatus of a conventional plating bath method (so-called cup method)as shown in FIG. 4. In this apparatus, an anode 202 made of phosphorouscontaining copper was set in a plating bath 201 to which a platingsolution was continuously supplied to overflow. A substrate 100 to beprocessed with a conductive layer 103 facing down as a surface to beplated was held at a plurality of hook-like cathode contacts 203, andthe conductive layer 103 and cathode contacts 203 were electricallyconnected. By moving down the substrate 100, the conductive layer 103was brought into contact with the plating solution to form a copperplating film on the surface of the conductive layer 103.

The copper plating thin film formed by impregnation had the same filmthickness (1 μm for 10 min) and resistivity (1.95 μΩ/cm) as those of thecopper plating film formed by the conventional cup method. No film wasformed at a portion where the substrate and impregnated pad did notcontact each other, and the periphery, bevel, and lower surface of thesubstrate were not contaminated.

The impregnation method and cup method, and the results of comparisonbetween the copper plating films formed by the respective methods willbe explained. Impregnation was done for a sample having a structure asshown in FIGS. 5A and 5B. FIG. 5A is a plan view showing the schematicstructures of the apparatus and substrate to be processed, and FIG. 5Bis a sectional view taken along the line 5B-5B in FIG. 5A. A platinghead 310 is placed on a substrate 100 to be processed. The plating head310 is comprised of an impregnated pad 311 containing a plating solutionthat is directly mounted on the substrate, and an anode set on theimpregnated pad.

The current density was 5 mA/cm², the plating time was 5 min, theplating solution was a mixture of hydrochloric acid in a CuSO₄-basedsolution, and the Cu content was 0.9 mol/Liter. In impregnation, twocases were compared: the plating head 310 was kept at a standstill witha gap being adjusted to 1.7 mm between the anode 312 and a conductivelayer 103, and the plating head 310 swung or scrolled. The filmthicknesses, variations, and resistivities of the respective copperplating films are shown in FIG. 6.

The film thickness of a copper plating film is higher in the swingmethod than in the remaining methods. This is because a portion madethin at the outermost periphery of the copper plating film was notmeasured, and the average of the thicknesses of the entire film isconsidered to be equal to those in the remaining methods.

Thickness variations of a plating film formed by the impregnation methodwere reduced in comparison with a plating film formed by the cup method.In particular, thickness variations of a film formed by keeping the headat a standstill were reduced by about 60%. The resistivity of a platingfilm formed by the impregnation method was also lower than that by thecup method.

SECOND EMBODIMENT

FIGS. 7A and 7B are views showing the schematic structure of a platingapparatus according to the second embodiment of the present invention.FIG. 7A is a plan view showing the schematic structure of the platingapparatus including a substrate to be processed, and FIG. 7B is asectional view taken along the line 7B-7B in FIG. 7A.

A plating head 410 is placed on the surface of a substrate 100 to beprocessed. The plating head 410 is comprised of an impregnated pad(impregnated member) 411 directly placed on the substrate, and an anode412 which is set on the impregnated pad 411 and connected to a powersupply 441. The anode 412 made of a mass of phosphorous containingcopper has through holes 413 having a diameter of 0.5 mm. A platingsolution in a plating solution tank 443 is properly supplied to theimpregnated pad 411 through the through holes 413 by a pump 442. Thethrough holes 413 formed in the anode 412 are very effective in order toremove bubbles generated by various causes in plating. Note that theanode 412 can be made of a copper wire mesh to attain the same effectsas those of the anode having holes. The mesh is formed by knitting a0.2-mm φ copper wire into a net. Alternatively, an anode formed byadding platinum to a porous metal material or porous carbon may beemployed.

Eight needle-like cathode contacts 420 are set outside the region of achip pattern 440 on the substrate 100. The conductive layer 103 of thesubstrate 100 is electrically connected to the cathode contacts 420.

The substrate 100 is placed on an X-Y stage 444. In forming a platingfilm, movement of the X-Y stage 444 is controlled by an X-Y stagecontroller 445 to scan the surface of the conductive layer 103 of thesubstrate 100 with the impregnated pad 411. In the second embodiment,the conductive layer 103 was repetitively scanned at a scanning rate of100 mm/s.

The X-Y stage controller 445 is connected to the power supply 441, andreceives a plating current only when the plating head exists in theregion of the chip pattern 440, so as not to form any plating filmoutside the region of the chip pattern 440.

The plating solution is appropriately supplied through the through holes413 formed in the anode 412 during scanning to replenish the impregnatedpad 411 with the plating solution so as not to run out the platingsolution in the impregnated pad 411. If some of the through holes 413are used as plating solution circulating strainers, a fresh platingsolution can be supplied by circulating the plating solution.

In scanning the plating film formation region with one stroke, theimpregnated member may be slid while a current is kept supplied.

When a copper plating film is formed using the above apparatus, theimpregnated pad 411 rubs a copper plating film 406 formed on an uppersurface 105 of the substrate by relative movement of the impregnated pad411 and Si substrate, as shown in FIG. 8. Hence, almost no thin film isformed from the plating solution additive on the upper surface 105, andthe additive acts in only a depression 104.

If a soluble copper complex compound (generally called a carrier) suchas disulfide [HS0 ₃—R—S═S—R—SO₃H] is added as an additive, the formationrate of the plating film increases on the surface where the additiveexists. As a result, film formation in a depression such as a groove orhole preferentially occurs. Also in the first embodiment, the platingrate is different between the upper surface of the substrate and thedepression. This difference further widens in the second embodiment.

The copper plating film 406 formed by the apparatus becomes very smooth,as shown in FIG. 9A. The film can be smoothened more easily than acopper plating film 407 (FIG. 9B) formed by the above-described cupmethod.

Note that the plating rate of the copper plating film on the uppersurface of the substrate changes depending on the pressure applied tothe impregnated pad. The pressure dependency of the plating rate of thecopper plating film is shown in FIG. 10. As is apparent from FIG. 10,the depression and the upper surface of the substrate have almost nodifference in the plating rate of the copper plating film for a lowpressure. As the pressure increases, the plating rate on the uppersurface of the substrate decreases.

In the above-described embodiments, the impregnated pad 411 was incontact with the conductive layer 103 or plating film 406 as shown inFIG. 8. However, the impregnated pad 411 may be set so as to be apartfrom the conductive layer 103 or the plating film 406, that is, to facethe conductive layer, as shown in FIG. 26. With this arrangement, adynamic pressure is generated in the plating solution due to relativemovement. A pressure difference between an inside and an outside of thedepression 104 caused by the dynamic pressure can make the plating rategreater in a groove or a hole than that on the upper surface of thesubstrate.

The copper plating film formed using this apparatus is formed on onlythe chip pattern surface. No film is formed at a portion except for thechip, which is effective for cleaning and the like. For example, sinceno copper plating film is formed at the edge of the substrate,contamination of the apparatus in the next step can be easily avoided.

Defects of the plating film caused by bubbles and dust in the platingsolution are greatly reduced. This is because bubbles are removed fromholes formed in the anode, and the impregnated pad moves on thesubstrate to prevent bubbles and dust from staying at one portion.

THIRD EMBODIMENT

FIGS. 11A and 11B are views showing the schematic structure of a platingapparatus according to the third embodiment of the present invention.FIG. 12 is a block diagram showing the schematic arrangement of theplating apparatus according to this embodiment.

As shown in FIG. 11A, the impregnated member of a plating head accordingto the third embodiment is formed from a band-like impregnated cloth 511connected like an endless loop. An anode 512 and two rollers 513 areattached to the inner surface of the band-like impregnated cloth 511,and the endless-looped impregnated cloth 511 has a trapezoidal shape.

As shown in FIG. 12, the anode 512 is made up of a plurality of anodes512 ₁ to 512 _(n) respectively connected to power supplies 541 ₁ to 541_(n) via selectors 651 ₁ to 651 _(n). In the third embodiment, platinumis used as an anode material. Platinum has a long service life becauseit does not dissolve in copper plating solution. Note that copper ionsin a plating solution decrease with a plating current.

The anodes 512 ₁ to 512 _(n) are respectively connected to capacitancemeters 652 ₁ to 652 _(n) and resistance meters 653 ₁ to 653 _(n) via theselectors 651 ₁ to 651 _(n). Each capacitance meter 652 and resistancemeter 653 measure the electrostatic capacitance and resistance betweenthe anode 512 and a substrate 100 to be processed. Based on themeasurement results, a gap controller 654 obtains the gap between theanode 512 and the surface of the substrate 100, and controls pushers 514₁ to 514 _(n) to control the gap between the substrate 100 and anode512. The parallelism between the anode and substrate and the absolutevalue of the distance between the anode and substrate, which areimportant in the present invention, can be managed by measuring andadjusting gaps at a plurality of portions.

Each power supply 541 is connected to a plating condition controller655. The plating condition controller 655 makes the thickness of theplating film uniform by controlling a plating current value supplied toeach anode 512 in accordance with the position of the substrate. Theplating condition controller 655 is connected to each capacitance meter652 and resistance meter 653, and controls a plating current valuesupplied to a corresponding anode 512 in accordance with the measurementresults of the meters 652 and 653.

A plating solution composition sensor 551 formed from a pH sensor is seton the trapezoidal impregnated cloth 511, and measures the pH of theplating solution contained in the impregnated cloth 511 to obtain thecomposition of the solution. The composition sensor 551 may obtain thecomposition of the plating solution by using an ammeter in addition tothe pH sensor and measuring the conductance of the plating solutioncontained in the impregnated cloth 511. Instead, the composition sensor551 may use an optical sensor which utilizes light absorption of thesolution.

In accordance with the measurement results of the composition sensor551, a composition controller 650 controls pumps 658 ₁ and 658 ₂respectively connected to a plating solution tank 656 and CuSO₄.5H₂Otank 657. Accordingly, the composition controller 650 controls theamounts of plating solution and CuSO₄.5H₂O supplied to the impregnatedcloth 511 from a plating solution supply nozzle array 552 and CuSO₄.5H₂Osupply nozzle array 553, and adjusts the composition of the platingsolution contained in the impregnated cloth 511.

The plating solution is appropriately supplied from the nozzle array 552to the impregnated cloth 511. As described above, the third embodimentuses a platinum electrode for an anode, so that copper ions in theplating solution decrease with the progress of plating. This becomesconspicuous particularly in the use of a thin sheet-like impregnatedmember. This solution composition adjusting mechanism is therefore veryeffective for improving stabilization of plating conditions. When a thinband-like impregnated cloth connected like an endless loop is adopted asin the third embodiment, the composition of the plating solution can beeasily adjusted at a place apart from the plated surface.

As shown in FIG. 13, a cathode contact 520 electrically connected to theconductive layer 103 of the substrate 100 is laid down at the outermostperiphery of the substrate 100, and fixed by a resin 521. Since thecathode contact 520 is fixed by the resin, even if plating head 510rides on the cathode contact 520, the impregnated cloth 511 and cathodecontact 520 do not directly contact each other, and the cathode contact520 is not disconnected from the conductive layer 103.

In order to form a plating film with a uniform film thickness using thisapparatus, attention must be paid to the fact that the effective area ofa substrate to be plated changes with movement of the substrate. Forthis reason, the plating current supplied to the anode is controlled inaccordance with a change in area.

For example, assume that the diameter of the substrate 100 is 200 mm,and the contact width between the substrate 100 and impregnated cloth511 in a direction parallel to the scanning direction is 10 mm, as shownin FIG. 14A. As the conditions of the plating current supplied to theanode, an optimum current value obtained in advance from the position ofa substrate which reciprocates at a constant speed may be used, as shownin FIG. 14B. The area may be calculated from the capacitance orresistance to sequentially perform plating at a constant currentdensity. Alternatively, the moving speed of the substrate may be changedto supply a constant amount of electric charges to the entire platedsurface.

FIGS. 15A to 15C are a view and graphs, respectively, showing theuniformity of a plating film formed at a constant voltage on a substrateto be processed. Cathode contacts are set at eight points NNE, ENE, ESE,SSE, SSW, WSW, WNW, and NNW in FIG. 15A. The diameter of the substrateis 200 mm, the plating current is 20 mA/cm², and the CuSO₄ concentrationin the plating solution is 75 g/Liter.

FIG. 15B is a graph showing the uniformity of the plating film by linesegments connecting middle points between adjacent cathode contacts,i.e., line segments indicated by solid lines in FIG. 15A. FIG. 15C is agraph showing the uniformity of the plating film by line segments eachconnecting cathode contacts, i.e., line segments indicated by dottedlines in FIG. 15A.

As is apparent from FIGS. 15B and 15C, the plating film varies dependingon the position from the cathode contact. The power supply controllerchanges a voltage applied to the anode in accordance with the detectionresults of a position sensor (not shown), and controls the platedthickness uniform on the substrate surface. This control is done bymeasuring the in-plane plated thickness distribution after a platingfilm is formed on a substrate at a constant voltage in advance, andcalculating from the measurement results a voltage distribution whichprovides a uniform film thickness.

In the third embodiment, film plating with a uniform film thickness isperformed on the substrate surface. In some cases, however, the filmthickness at the periphery of the substrate may be wanted to be madesmall or large for post-process convenience. Also in such case, adesired film thickness distribution can be attained by properly changinga current/voltage applied to each anode or the moving speed of thesubstrate.

A cleaning head, field etching head, and CMP head having similarmechanisms to that of the apparatus can be adopted to realize anapparatus capable of performing parallel processes.

Further, a plated-thickness meter using, e.g., an eddy current generatedby electromagnetic induction is installed as a film thickness monitor infront of the head. Film formation is executed while the film thicknesson the substrate surface is measured on the forward path of the platinghead which reciprocates, and the plating current, the moving speed ofthe substrate, and other plating conditions are controlled on the returnpath based on the measurement results. This enables precisely managingthe final film thickness.

FOURTH EMBODIMENT

The fourth embodiment will exemplify a plating method using a smallerplating head than a substrate to be processed.

FIG. 16 is a view showing the schematic structure of a plating apparatusaccording to the fourth embodiment of the present invention. A 200-mm φsubstrate 100 is plated using a 20-mm φ plating head 1010 smaller thanthe substrate.

The plating head 1010 made up of an impregnated pad 1011 and anode 1012comprises a moving mechanism (not shown) which can move up and down,right and left, and forward and backward, and a position sensor 1041 formonitoring the moving position. A plated-thickness monitoring sensor1042 using electromagnetic induction is also set near the head 1010.

Cathode contacts 1020 are set as platinum contacts at six portions onthe outermost periphery (about 1 mm on the periphery) in order to avoidany contact scratches because an LSI chip in process is present on thesubstrate (8-inch wafer) 100 except for its periphery. A 100-nm thickcopper film is sputtered on the substrate 100 in advance as a conductivelayer for forming a plating film.

To supply a plating solution to the impregnated pad 1011 (or replace anold plating solution with a new one), the plating head 1010 iseffectively moved to a plating solution reservoir 1043 by a movingmechanism and swung vertically and horizontally so as to press the head1010 against the bottom of the plating solution reservoir 1043.

When the cathode contact is set at the outermost periphery of thesubstrate 100, as described above, the plating rate on the substratesurface changes upon constant-voltage plating because of a thinconductive layer and high resistance. Experimental results revealed thatthe film thickness decreased about 30% near the center. This trendbecomes more typical as the conductive layer material increases inresistance or decreases in thickness.

The voltage varies for a constant plating current, which varies theplating film quality (crystallinity, filling performance, flatness, andthe like) on the substrate surface. Thus, plating is executed at aconstant voltage while the distance between the anode and the surface ofthe plating film is controlled to control the current. The platedthickness is measured by the film thickness sensor 1042, and the platinghead 1010 is repetitively moved to repeat plating until a target filmthickness is attained. Accordingly, a desired film thickness (determinedby total electric charges received by a target surface) can be obtainedby constant-voltage plating regardless of the distance from the cathodecontact 1020.

When the substrate has a groove pattern, the impregnated pad is alsoeffectively swung vertically and horizontally using an ultrasonicoscillator in order to prompt circulation of the plating solution.

Instead of repeating plating with the above plating head until a desiredfilm thickness is obtained, selective plating may be performed byselectively bringing the distal end of a pen-like impregnated padsmaller than the impregnated pad of the head into contact with theconductive layer and moving the impregnated pad in accordance with thefilm thickness distribution.

FIFTH EMBODIMENT

The fifth embodiment proposes the structure of an apparatus in which thedistance between the anode and cathode is always kept constant to easilymake the plated thickness uniform.

FIG. 17 is a sectional view showing the schematic structure of a platingapparatus according to the fifth embodiment of the present invention. Ina plating head 1110 according to the fifth embodiment, an anode 1112equal in diameter to a pad 1111 is set on the columnar impregnated pad1111 that contains a plating solution. A dielectric isolation layer 1113is formed on the impregnated pad 1111 and anode 1112. An impregnated pad1114 which is almost equal in thickness to the impregnated pad 1111,made of the same material as the pad 1111, and contains an electrolyticsolution is formed on the isolation layer 1113. A doughnut-like cathode1115 equal in inner and outer diameters to the impregnated pad 1114 isset on it. A hydrophobic outer ring layer 1116 is formed on theimpregnated pad 1114 and cathode 1115.

As the electrolytic solution contained in the impregnated pad 1114, a10% aqueous hydrochloric acid solution is used. Hydrochloric acid, whichdoes not corrode a copper plating film, is suitable for forming a copperplating film. Note that the electrolytic solution is not limited tohydrochloric acid, and can be an arbitrary solution so long as it doesnot corrode the plating film.

According to the structure of the apparatus, the cathode is electricallyconnected to the substrate through the electrolytic solution containedin the impregnated pad 1114, and the cathode 1115 and anode 1112 areelectrically connected through the plating solution, the conductivelayer on the substrate surface, and the electrolytic solution. As aresult, a plating film is formed on the substrate on which theimpregnated pad 1111 is placed on the surface.

According to this apparatus, the anode and cathode move with a distancealways kept constant, so that a uniform film can be formed. The sameeffects can also be attained by the following structure. That is, theplating solution-impregnated pad and anode are replaced with theelectrolytic solution-impregnated pad and cathode. The electrolyticsolution-impregnated pad and cathode are formed into a columnar shape,and the plating solution-impregnated pad and anode are formed into adoughnut shape.

SIXTH EMBODIMENT

The sixth embodiment will exemplify a technique of forming a bump on asemiconductor chip or the like using the above-described impregnationmethod.

A method of performing bump processing for a semiconductor chip includesa method of electroplating a substrate in a plating bath using aphotoresist or the like as a mask, and a method of press-fixing a ballto a substrate. The plated thickness generally used in a bump is about100 times that in the LSI thin film process, i.e., in the order of 100μm. Therefore, film plating is not negligible with respect to thethickness (generally, several μm to several ten mm) of the impregnatedcloth. Moreover, different attention from the above-mentionedembodiments must be paid in terms of sufficient supply of a platingsolution to the distal end of the impregnation head.

The sixth embodiment concerns a simple high-precision bump platingtechnique using impregnation plating. The characteristic feature of thisembodiment is to form a thick film with the distal end of a fineimpregnated cloth (only the distal end may be sharpened).

FIG. 18 is a sectional view showing the schematic structure of a platingapparatus according to the sixth embodiment of the present invention. Animpregnation head 1210 has an impregnated material (impregnated member)1211 so as to cover a projected anode 1212 connected to a DC pulse powersupply 1240. The discharge ports of fine nozzles 1213 for supplying aplating solution, and the suction ports of fine strainers 1214 fordischarging the plating solution are arranged near the distal end of theimpregnated material 1211.

The plating solution supplied from each nozzle 1213 to the impregnatedmaterial 1211 is sucked by each strainer 1214. Accordingly, thecomposition (metal ion concentration or additive concentration) of theplating solution at the distal end of the impregnated material 1211 isalways kept constant.

If the nozzles 1213 and strainers 1214 are uniformly arranged, theplating solution discharged from each nozzle 1213 is immediately suckedby a corresponding strainer 1214, failing to satisfactorily supply theplating solution to the distal end of the impregnated material 1211. Toprevent this, the nozzles 1213 and strainers 1214 are preferably locallyarranged to satisfactorily supply the plating solution to the distal endof the impregnated material 1211.

In forming a bump, the impregnation head 1210 is retracted by a movingmechanism (not shown) along with plating of a plating film 1250. Bychanging the moving speed of the impregnation head 1210 or horizontallymoving it, bumps of various shapes can be formed. For example, a conicalbump 1241 (FIG. 19A), hemispherical bump 1242 (FIG. 19B), columnar bump1243 (FIG. 19C), and bump 1244 (FIG. 19D) having a shape of stackedballs can be formed.

SEVENTH EMBODIMENT

The seventh embodiment relates to a plating apparatus for intentionallyforming a plated thickness distribution (profile) corresponding to apattern on a substrate to be processed or a pattern within a chip.

FIG. 20 is a sectional view showing the schematic structure of a platingapparatus according to the seventh embodiment of the present invention.Note that FIG. 20 shows only an impregnation head, and no substrate,cathode contact, plating bath, and the like are illustrated.

Depressions corresponding to a pattern within a chip are formed on thesurface of an impregnated pad 1311 of a plating head 1310. An anode 1312is connected to the impregnated pad 1311.

For example, in a hybrid system LSI of a DRAM and logic, the DRAM partand logic part are greatly different in pattern density and size evenwithin the same chip. An optimal formation thickness for a subsequentstep such as CMP changes depending on the location. Thus, for example,one of the DRAM and logic parts is formed in the depression of thesubstrate, and a projection corresponding to the depression of thesubstrate is formed on the surface of the impregnated pad. Theprojection and side surface of the impregnated pad 1311 can betransformed by heat treatment or filler processing to pores, therebypreventing the plating solution from oozing out from the surface of theimpregnated pad 1311. It is also possible to form projections into smalldots in the order of several μm and change the density distributionthereof between the DRAM and logic parts.

Note that the technique of the seventh embodiment can be applied tosteps formed by the pattern density, pattern shape, size, and differencein height.

A method of forming such an impregnated pad will be explained withreference to FIGS. 21A to 21D.

AS shown in FIG. 21A, a rectangular prism-like impregnated pad 1311 andheated mold 1340 are prepared. As shown in FIG. 21B, the impregnated pad1311 is pressed against the mold 1340 to deform the pad 1311. At thesame time, the surface of the impregnated pad 1311 in contact with themold 1340 is dissolved to transform the surface so as to prevent aliquid from oozing out.

As shown in FIG. 21C, the pad 1311 is extracted from the mold 1340. Asshown in FIG. 21D, the lower portion of the impregnated pad 1311 isremoved to form a region from which a liquid oozes out.

As shown in FIGS. 22A and 22B, the projection of a heated mold 1342 maybe pressed against part of the surface of a pad 1341 (FIG. 22A) totransform part of the surface of the pad 1341 (FIG. 22B). The pad formedby this formation method has the same effects as those of the pad shownin FIG. 20 because supply of the plating solution to the substratechanges between the location against which the mold is pressed and thelocation against which the mold is not pressed.

The in-plane plated thickness can also be changed by arranging inside animpregnated pad 1351 a plurality of anodes 1352 corresponding to thesteps of the substrate surface, and changing potentials applied to therespective anodes 1352, as shown in FIG. 23.

The in-plane plated thickness can also be changed by uniformly formingan anode 1362 on the surface of an impregnated pad 1361, and formingintermediate electrodes 1363 in the pad 1361 so as to apply a fieldcorresponding to the steps of the substrate surface, as shown in FIG.24. This is because plating conditions such as the ion concentration andfield distribution near each intermediate electrode 1363 changedepending on the potential applied to the intermediate electrode 1363.Similarly, an insulator can be used in place of the intermediateelectrode 1363.

EIGHTH EMBODIMENT

The eighth embodiment will exemplify an apparatus in which a pluralityof impregnated pads are attached to an impregnation head and playdifferent roles.

FIG. 25 is a view showing the schematic structure of a plating apparatusaccording to the eighth embodiment of the present invention. Theapparatus of this embodiment comprises an endless-looped impregnatedbelt 1411 obtained by connecting four impregnated cloths A, B, C, and Dthrough isolation regions 1412 including a repellent, spaces,non-impregnated material. The impregnated cloths A, B, C, and D containdifferent liquids and have different functions. The impregnated clothsA, B, C, and D act on a substrate 100 to be processed by rotating theimpregnated belt and bringing an arbitrary impregnated cloth intocontact with the substrate 100.

The functions of the impregnated cloths A, B, C, and D includeelectroplating, electroless plating, electrolytic etching, physicalscratching, chemical treatment, chemical mechanical polishing, and purewater cleaning. Different plating solutions may be contained in therespective impregnated cloths.

Note that the present invention is not limited to the above embodiments.A copper film has been exemplified as a plating film to be formed.However, a material other than copper may be formed into a plating film.

The layout of the substrate and impregnated member is not limited to theabove embodiments. The impregnated member may be brought into contactwith the conductive layer while the substrate and impregnated member areinclined, or the substrate may be placed on the impregnated member.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventiveconcept as defined by the appended claims and their equivalents.

1-21. (canceled)
 22. The plating method comprising the steps of:preparing a substrate to be processed which has a base plate and aconductive layer formed on at least part of the base plate; applying apotential of a cathode to the conductive layer; and forming a platingfilm on at least part of a region by causing an impregnated membercontaining a plating solution in electrical contact with an anode toface the conductive layer, wherein the step of forming a plate filmincludes the step of forming a plating film while alternately repeatingan operation of causing the conductive layer and the impregnated memberto face each other and an operation of moving the impregnated member toa remote location where a plating current is interrupted between theanode and the cathode.
 23. The method according to claim 22, wherein theoperation of moving the impregnated member to a remote location includesan operation of dipping the impregnated member into a plating bathcontaining the plating solution.
 24. A plating method comprising thesteps of: preparing a substrate to be processed which has a base plateand a conductive layer formed on at least part of the base plate;causing an impregnated member containing a plating solution inelectrical contact with an anode to face the conductive layer in orderto form a plating film in at least part of a region; and connecting acathode to the conductive layer by causing another impregnated memberwhich contains an electrolytic solution and is connected to the cathode,to face the conductive layer in a different region from a region wherethe impregnated member comes into contact with the conductive layer. 25.The method according to claim 24, wherein the conductive layer is incontact with at least one of the impregnated member and the anotherimpregnated member.
 26. The method according to claim 24, wherein theanother impregnated member performs the same sliding movement as theimpregnated member.
 27. A plating method comprising the steps of:preparing a substrate to be processed which has a base plate and aconductive layer formed on at least part of the base plate; causing animpregnated member containing a plating solution in electrical contactwith an anode to face the conductive layer in order to form a platingfilm in at least part of the conductive layer; connecting a cathode tothe conductive layer by causing another impregnated member whichcontains an electrolytic solution and is connected to the cathode, toface the conductive layer in another region than a region where theimpregnated member faces the conductive layer; and measuring a filmthickness of the plating film by a film thickness measuring mechanismarranged on the conductive layer in still another region than the regionwhere the impregnated member faces the conductive layer.
 28. The methodaccording to claim 27, further comprising the step of additionallyforming the plating film by causing the impregnated member to face theconductive layer in accordance with a measurement result of the filmthickness measuring mechanism.
 29. The method according to claim 27,wherein the film thickness measuring mechanism performs the samehorizontal movement as the impregnated member. 30-44. (canceled)